There is no way other than doing a receive() or match() polling operation. Also note that if you transmit data to the serial port using send() or match(), that the existing buffer is cleared.

This behavior makes it more difficult (read as not 100% reliable) to do full-duplex communication as prior to a send, you must always do receive() or match() prior to send() or match() and there is always a small window that can occur where you blow away data that is in the buffer.

Assuming you are using async model for serial port, you can do:

s.receive(1024,125); // initial read to drain the buffer waiting only 125ms.
// data will be delivered asynchronously either in onData() or onTimeout()
// callback - onTimeout will be called if less than 1024 bytes of data.
s.match(toSend,"\r",1000);

Yes, to me, this is very quirky. Almost makes for easier programming to do the serial operation synchronously. In fact, that is exactly what I do with my X10 module. :-)